I don't think it referred directly towards her morganatic lineage since it wasn't her Teck hands commented on but her Wurttemburg hands. I think that QM had rather large hands (she almost never had them photographed, either wearing gloves or holding something) and was a bit sensitive about them. It was just a mean-spirited slap (the Wales girls, save for Maud, were very possessive of their only surviving brother) along the lines of Toria's 'she's a dreadful bore' comment.